1. Field of the Invention
This invention relates to dishwasher apparatus, and in particular to means for controlling the dispensing of dishwashing liquid additives selectively in the operation of the dishwasher apparatus.
2. Description of the Background Art
In U.S. Pat. No. 4,134,003 of Ronald E. Hahn, which patent is owned by the assignee hereof, a dishwasher control is shown wherein the heater of the dishwasher is connected selectively directly across the power supply or in series with a detergent dispenser operator heater element. The control utilizes a timer having six timed switches, each comprising a single pole switch. One of the timer switches is connected between the power supply lead and the heater and another of the timer switches is connected between the power supply lead and the detergent dispenser heater element.
Mabel A. Voris shows, in U.S. Pat. No. 2,181,983, an automatic dishwashing machine having a plurality of controls for causing the dishwasher to provide an automatic dishwashing cycle.
In U.S. Pat. No. 2,914,073, Myron E. Ullman, Jr. shows a dishwasher construction utilizing a plurality of single pole, double throw switches in the control thereof. The circuitry is complex and is arranged to connect the controlled elements in a specific arrangement disclosed.
In U.S. Pat. No. 3,177,380, James W. Jacobs shows an impulse timer for use in a dishwasher in a circuit utilizing a single pole, double throw switch and a single pole, single throw switch to actuate two different dispensers and a heater circuit.
George E. Keifer et al show, in U.S. Pat. No. 4,213,313, a dishwasher control circuit employing four relays to provide eight operating functions. The control selects transitional relay combinations between operative combinations to prevent inadvertent initiation of a function which might otherwise occur as a result of a race condition in switching the relays.